Our research has been directed toward delineating the machinery employed by living cells to translate the genetic information encoded in messenger RNA. These experiments have been carried out primarily in bacteria and viral infected bacteria. While continuing to probe deeper into the mechanism of how enzymes are synthesized in E. coli, we are in the process of extending these studies to examine the control of translation in mammalian cells. Many scientists have as their ultimate goal the desire to understand the genetic controls operative during cellular differentiation. However, most systems which exhibit differentiation are not suitable for detailed genetic analysis at this time because of their inherent complexity. A eukaryotic system which is approachable is a mammalian cell programmed by a mammalian virus. The interaction between the host cell and the viral genome provides an excellent system for exposing the spectrum of controls present in the host cell as well as control systems developed by the virus to exploit its host. The power of this system is that through the virus it is amenable to genetic analysis. It is for this reason that we are devoting a major proportion of our research effort towards expanding the genetic tools available to researchers in mammalian virology. In particular, we are developing the technology for isolating suppressor sensitive mutants of mammalian viruses, including the DNA and RNA oncogenic viruses. The availability of such mutants would not only prove invaluable to study numerous cellular aberrations of viral origin but also provide new tools for examining control processes in the host cell.